Process of producing positive plates for batteries.



Patented lune 5, I900.

No. 65|,089. a. STRECKER.

PROCESS OF PRODUCING POSITIVE PLATES FOB BATTERIES.

' (Application filed Kay 12, 1899.)

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TATES A'IENT HANS STRECKER, OF COLOGNE, GERMANY.

SPECIFICATION forming part of Letters Patent No. 651,089, dated June 5, 1900. Application filed May 12,1899. Serial No. 716,605. (No specimens.)

To all whom it may concern:

Be it known that I, HANS STRECKER, a subject of the King of Prussia, Emperor of Germany, residing at Oologne-ou-the Rhine, Germany, have invented certaidnew and useful buch der Elektrotechnik, Grawinkel dz K.

Strecker, 5th Edition, pages 366 and 367 In order to attain this object, the plates are specially constructed, as shown in the accompanying drawings, which form part of the present specification, and in which- Figure 1 is an elevation ofa plate embodying my invention, and Fig. 2 is a horizontal section on the line a roof Fig. 1.'

The interior part of the plate, which is never so much used as the edges, the latter being almost exclusively effective in supplying the current-,is removed entirely, the plates being provided at this part with a circular,

oval, square, or other shaped orifice lined or edged with a hard leadflframe or rim. The side of this rim, which is turned toward or contacts with the mass, is provided with a groove adaptedtogrip the mass and retain the same properly in position, the said ring or rim being retained in its position by the mass itself. This ring or frame of hard lead is advantageously made in two parts, which are not quite close together, so as to allow for the expansion of the mass. 4

In the drawings" a represents the mass, 1) the exterior frame, and c c the divided interior frame. The arrangement of this central frame or ring disposes of a part of the mass, which practically only forms deadweight and which gives rise in the main to the warping of the plates previously mentioned. As a secondary result of this arrangement more space is attained for the sulfuric acid and a better circulation efiected. A special process is necessary in order to arrange the ringin position. This process must render it possible in filling to lay on the efiective mass in as dry a condition as possible and without a subsequent drying process to form the plate as rapidly as possible, since the methods generally employed of filling the frame with wet mass and subsequently drying the same in a furnacefor instance, Boeses prOcesscauSe the effective mass to contract and become loose, so that a ring arranged in the interior of the mass would fall out of the plate and the massitself would crumble owing to the fragility of the plate before the same becomes hardened in the sulfuric acid. This process will be described hereinafter; but it should be mentioned here that in order to attain the desired result the employment of litharge is particularly advantageous. Hitherto the employment of litharge alone for positive plates has been objected to because it produced too dense and hard plates,which did not show sufficient capacity owing to their slight porosity and which were apt to warp during the formation. Red lead exclusively was used for the positive plates, and for the negative plates a mixture of red lead and litharge. The production of mass-plates is based on the action of the sulfuric acid on red lead or litharge even in those processes in connection with which it is alleged that the addi tion of a binding medium of organic nature and the formation of organic lead salts causes the hardening. The reaction which takes place between red lead or litharge and sulfuric acid causes the reacting mixture to expand in volume, so that if the mass is in a frame when the reaction takes place it will jam and become hard, or, in other words, the formation of sulfate of lead affects the hardening. This method of manufacturing has two considerable disadvantages, both of which are easily obviated by means of the present process with litharge. In the first place when red lead is employed thereis the disadvantage that the red lead of commerce shows various chemical formulae, (generally Pb O and Pb 0 This difierence in the formulae causes an unequal formation of lead sulfate in the hardening process, and consequently inequality in the hardness and capacity of the plates. The difference in the reaction of various red leads with sulfuric acid will be apparent from the following formulae:

In the second place, the hardening of the plates is generally attained by dipping the raw plates in sulfuric acid. In order to effect this, it is necessary to carefully dry the plates, so as to prevent their bursting when dipped into the acid. The drying process,however, as also the present popular admixture of organic substances cause the formation of an exterior crust on the-surface of the plates,

in action,causing inconvenience and the commencementof the destruction of the plates. According to the present process, as above stated, the effective raw mass is employed in as dry a condition as possible in order to enable the-rings to be fixed up. Then, again, instead of red lead a mixture of litharge and carbonate of lead is employed, the amount of the latter substance being suflicient to cause the expansion of'the mixture when r acting with sulfuric acid to equal that of red lead of the formula Pb Q, when hardening. Since lead carbonate during its conversion into sulfate of lead does not suifer any increase of volume, the addition of the carbonate to the litharge has the effect .of decreasing the total expansion of the product of the reaction. This requirement will be fulfilled, as a rule, by amixture consisting of eightyfive to ninety-two per cent. litharge and fifteen to eight per cent. of carbonate of lead.

It is known that lead oxid mixed with carbonate of lead has been employed for making accumulator-plates having a soft mass, (category lattice-plates.) This was done, however, for other reasons than thepresent ones, the main object having been to decrease the expansion of the litharge on its reaction with sulfuric acid by the presence of the carbonate of lead. According to German Patent No.

27,203, for instance,- besides the white lead organic substances were added to the lead oxid in order to attain greater porosity of the plates, in that the organic substance was' carbonized and the carbonic acid of the carbonate (in contradistinction to the present proc ess) was driven off before the formation by heating the plates. According to the present invention the above-mentioned oxid mixture .is slightly moistened with it dilute alkaline fifteen per cent. of sulfate-of-soda solution with a little sulfuric acid in order to prevent the formation of crusts;

Instead of the acidulated sulfate-of -soda so 'lution another acidulated salt solution may be employed-for instance, a potash, ammo '.nium, or magnesium sulfatesolution acidulated with sulfuric acid. which crust soon falls oil? when the plates are t The above solutions have beeneinployed for forming previous to the present a'pplication; but} the combination of the same with the above pasting method is noveland forms, together with this method, an indivisible whole.

I claim as my invention 1. A process for producing positive massplates, having the central portion omitted for use in connection with electric accumulators,

said plates being composed of a mixture of litharge and lead carbonate, characterized by mixing litharge with lead carbonateztofltorm a mass containing preferably eighty fiv'e to ninety-two per cent. of litharge, andfifteen to eight per cent. of lead carbonate, slightly moistening the above mass with a dilute alkaline solution; pasting it hetweenan outer and an inner frame lying in the same plane, and forming it while damp in an acidulated salt solution, substantially as described.

2. An electrode plate for electric accumulators, consisting of a frame having a filling composed of eighty-five to ninety-two per cent. of litharge, and fifteen to eight per cent.

, of lead carbonate moistened with a dilute alkaline solution, and having the'central part removed, and bordered by arim orinner frame in order to prevent the plate from warping and to enable a better circulation of the acid in the manner and for the purpose substantially as described.

Signed at Cologne-on-the-Rhine, Germany, this 1st day of May, 1899.

HANS S'IREOKER. Witnesses:

CHAS. E. BARNES, WILLIAM H. MADDEN. 

